What is gigantism?

Gigantism is a rare condition caused by too much growth hormone. It will cause your child to grow faster than normal. It can appear at any time from childhood to adolescence.

Adults can get a similar condition called acromegaly. Acromegaly does not make you grow taller, as your growth plates are fused. It causes changes to your facial features and larger than normal hands and feet.

What are the symptoms of gigantism?

The main symptoms of gigantism are caused by too much growth hormone. They are:

• tall height
• a noticeable forehead and jaw
• large hands and feet, with thick fingers and toes
• more sweating than usual
• skin tags
• joint pain

A tumour in the pituitary causes gigantism in some children. The size of the tumour will affect the symptoms that your child gets. A large tumour can cause:

• headaches
• eyesight problems
• delayed puberty

What causes gigantism?

Gigantism is caused by high levels of growth hormone during childhood and adolescence. Growth hormone is made by the pituitary gland in your brain.

Growth hormone works with insulin-like growth factor 1 to cause cell growth.

High levels of growth hormone are almost always caused by a benign tumour (not cancer) on the pituitary gland. The type of tumour is called an adenoma.

There is usually no clear reason why the adenoma grows. In rare cases, it may be due to a genetic health issue.

When should I see my doctor?

See a doctor if you are concerned about:

• your child's rate of growth
• the size of your child’s hands or feet
• your child’s face shape changing

How is gigantism diagnosed?

Your doctor will examine your child. They will ask you questions about your child’s health.

Tests to diagnose gigantism include:

• blood tests — to measure levels of the hormones growth hormone and insulin-like growth factor 1
• oral glucose tolerance test — to see how growth hormone levels change when blood sugar level is increased
• an MRI or CT scan — to look at the pituitary gland

Your doctor may also arrange for your child to have:

• eyesight testing
• an echocardiogram
• a sleep study
• genetic testing

How is gigantism treated?

Treatment for gigantism should begin as early as possible. These treatments include:

• surgery — to remove or reduce the pituitary tumour
• medicines — to control your child’s levels of growth hormones
• radiotherapy — to destroy tumour cells and help control growth hormone levels

In some children, surgery will cure the condition.

Living with gigantism

Your child will need yearly checks with your doctor and blood tests. These check their growth hormone and insulin-like growth factor 1 levels.

It can be hard to buy items such as clothes, shoes and furniture. This can affect your child’s quality of life and lead to mental health problems.

What are the complications of gigantism?

Gigantism can cause:

• muscle weakness
• osteoarthritis
• sleep apnoea
• heart issues
• diabetes

Successful treatment can prevent serious complications.

Can gigantism be prevented?

The tumour that causes gigantism can’t be prevented. However, early detection and treatment can prevent many of the long-term consequences.

Resources and support

To learn more about pituitary conditions visit the Australian Pituitary Foundation.

Find out how you can support your child’s mental health.

If you want to know more about gigantism, you can call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you, 24 hours, 7 days a week.